During oil and gas exploration and production, many types of information are collected and analyzed. The information is used to determine the quantity and quality of hydrocarbons in a reservoir, and to develop or modify strategies for hydrocarbon production. One technique for collecting relevant information involves monitoring electromagnetic (EM) fields.
Magnetic field sensors typically consist of wire coils and their related circuitry to measure the voltage induced in the wire coils by a time-varying magnetic flux density. The measured voltages are then communicated to a recording unit and/or central processing unit via an electrical telemetry system, which may employ one or more stages of signal amplification. While the sensors themselves can be designed with passive electronic components, the telemetry and amplification components require electrical power. In a downhole environment, this is not desirable.
It should be understood, however, that the specific embodiments given in the drawings and detailed description do not limit the disclosure. On the contrary, they provide the foundation for one of ordinary skill to discern the alternative forms, equivalents, and modifications that are encompassed together with one or more of the given embodiments in the scope of the appended claims.